You need to destroy your RAID array and then recreate it with a different strip size. That would delete all your data. If you do an image backup of your C and then restore it on the new RAID array, it should work.
NOTE: With the app "TreeSize professional", I looked at my C:\ to get the average file size:
C:\Program Files (x86) = 244.9 KB
C:\Windows = 248.1 KB
C:\Program Files = 381.8 KB
C:\games = 479.9 KB
C:\Users = 673.8 KB
Total average file size: 405.7 KB
The point is, with a 32 KB stripe, the granularity is excessive for a Windows 7 *DESKTOP* environment as you need to combine 2 stripes (1 from each drive) to get the smallest block size, which in this example is 64 KB (2 X 32 KB). In essence, a small strip add overhead to reconstruct files with too many small block size. The point of using a 32 KB strip would be to accelerate files of size down to 64K. File smaller than 64K in a 32 KB strip array would be stored on 1 drive up to 32KB and the rest on the second drive + empty space to fill the 64 block size, On the other hand, much bigger files would be stripped to death in a lot of (too many) small 32 KB stripes, reducing speed because of the reconstruction overhead.
A 48 KB file would be saved as 1 X 32 KB part on drive 1 and 1 X 16KB part on drive 2 + 16 KB of empty space = 1 X 64 KB block size. That would only partially accelerate loading this file as not 100% of the file is split across 2 drives.
A 6144 KB file would be saved as 96 X 32 KB part on drive 1 and 96 X 32 KB part on drive 2 = 96 X 64 KB block size. That would accelerate the loading of this file BUT you'll need to join back 192 stripes to reconstruct the file. With a 128 KB stripe, the same file would be stored as only 24 part X 128 KB on each drive, requiring only 48 stripes to be join back to reconstruct the file. That's 4 times less overhead!
16KB, 32KB and even 64KB strip validity is more obvious in older OS using smaller file size (all files were generally smaller in Windows 95, 98 and XP compared to Vista, 7 and 8) and for server /database profile involving tons of very small files . As you can see, my C:\ drive has an overall average file size of 405.7 KB, which mean the vast majority of the files are over 256 KB, which is the perfect target file size of a 128KB stripe array.